95 993 cam sprocket question

F1addict · 01:15 PM

I’m in the process of replacing my cam box gaskets to fix a leak but as I’m dry fitting things back together I’m curious about a few things.
On the drivers side I have a thick washer and then 2 spacers. This pushed the flange sprocket out which seams to leave the cam sprocket on a portion of the cam that is not a very tight fit.
My question is that correct?
The other question I have is it it critical where the pin goes that indexes the cam sprocket to the flange?
The third thing I’m wondering about is which side of the cam sprocket faces out? I’m noticing the drivers and passengers are different.

TIA

F1addict · 05-22-2021, 01:45 PM

A link to the cam sprocket tolerance.
https://youtu.be/Lqg0tFu-1es

dannobee · 05-22-2021, 03:05 PM

The pin sets the cam timing. Screw this up and the pistons will hit the valves. There are various tutorials on youtube to guide you through the process.

https://www.youtube.com/watch?v=iHHp5o8lmOo

The left and right cam sprockets are interchangeable, they just get flipped around. Correctly installed the left side will be bowl shaped, the right side will be flush.

F1addict · 05-22-2021, 03:19 PM

Super helpful thank you!
How about the slop in the cam sprocket? Any thoughts?

F1addict · 05-23-2021, 11:02 AM

If I install it without the 2 shims the sprocket is able to center up on the cam but only because there is just a bit of a lip exposed.
Is it normal to not have room to install the shims?
I’ll try to measure the sprocket alignment tomorrow when I have a straight edge.

F1addict · 05-23-2021, 11:06 AM

I’ve tried it with one shim and that’s still to much.

JoeMag · 05-24-2021, 05:40 AM

Interesting the 993 cams are not same diameter all the way out... after market cams i've gotten and 964 cams i had are same diameter all the way out.

How many shims were on it when you took it apart? Did you just take cam boxes off and left rest of system (cam tower, heads, etc) on the motor?

F1addict · 05-24-2021, 06:16 AM

Quote:

Originally Posted by JoeMag

Interesting the 993 cams are not same diameter all the way out... after market cams i've gotten and 964 cams i had are same diameter all the way out.

How many shims were on it when you took it apart? Did you just take cam boxes off and left rest of system (cam tower, heads, etc) on the motor?

Same size all the way to the end would be helpful right about now.
Correct I just took the boxes off to replace the gasket and orings.
Both sides only had 2 shims, but I just don’t see how that can work correctly on the left side.

F1addict · 05-24-2021, 08:09 AM

The ends of each cam have varying depths for the thrust washer, shims, flange and sprocket to ride on which seems slightly odd since the left and right cam sprockets are interchangeable.

Left side

Right side

gled49 · 05-24-2021, 08:48 AM

You are trying to backdate from one piece chain sprocket to multi piece vernier system. The ends of the cams need to be welded up so the chain wheel will register on the cam. Chain alignment dictates the number of shims needed, period. Porsche cut down the diameter of the ends of the cam so you can’t backdate. Either it’s a later engine with one piece sprocket, or late cams were installed in the engine.

F1addict · 05-24-2021, 08:56 AM

Quote:

Originally Posted by gled49

You are trying to backdate from one piece chain sprocket to multi piece vernier system. The ends of the cams need to be welded up so the chain wheel will register on the cam. Chain alignment dictates the number of shims needed, period. Porsche cut down the diameter of the ends of the cam so you can’t backdate. Either it’s a later engine with one piece sprocket, or late cams were installed in the engine.

It’s a 95 with verio ram. My understanding is the cam sprockets are the same in a 964 as a 95 993. That had me scratching my head for a while because the cams in my book all only had 4 holes.

dannobee · 05-24-2021, 10:25 AM

Some time around 3/95 was the cutoff from early to late cams as gled describes.

gled49 · 05-24-2021, 06:45 PM

F1, u haven’t explained why u have late cams that belong with one piece chain sprockets. Are u backdating, did u buy this engine in a box. Did u change cams. How did u end up here.
The easiest way to go is install one piece chain sprockets.

F1addict · 05-24-2021, 06:55 PM

I bought the motor as is, all I was trying to do fix some leaks. As dannobe mentioned and is my understanding after some research early 95’s have these sprockets. I have since found out the 95 cam sprocket washer is slightly different. 95 has a lip for it that mates to the sprocket, but I still find it to not be a perfect solution. The inside of the cam is 30 mm while the end of the cam is 29.4. That’s 6 mill of slop on the sprocket to cam.

F1addict · 05-24-2021, 06:57 PM

95 part on right

F1addict · 04:13 PM

Assuming this is normal considering the
cams were timed and torqued down with the cam tensioning tools in place. Didn’t do it with them in place. Is this just because there is no oil pressure present?
The right side doesn’t seem as extreme but it is also on the bottom of the cam box and probably getting some oil passing through?

After assembly with tensioners
https://m.youtube.com/watch?v=TBWIdyhZesc

With tensioner
https://youtu.be/cTtCrEXBfI8